Some regions of the world such as rural, developing or isolated areas often have limited communication infrastructure where high speed broadband through traditional, ground-based (i.e. wired) means is not feasible. Providing an internet link via satellite enables such regions to obtain modern standards of internet access without the need to build a large amount of new infrastructure on the ground. Furthermore, satellite-based internet access can even be used as an alternative to ground-based links in regions that do have a developed communication infrastructure, or as backup to such infrastructure in case a ground-based link fails.
FIG. 1 gives a schematic overview of a system 100 for providing access to an internet 102, i.e. a wide area internetwork such as that commonly referred to as the Internet (capital I). The system 100 comprises a satellite gateway 104, a satellite 110 in orbit about the Earth, and one or more client systems 112 located in a region on the Earth's surface to which internet access is being provided. The satellite gateway 104 comprises a router 108 connected to the internet 102, and at least one satellite transceiver 106 connected to the router 108. Each of the one or more client systems also comprises a satellite transceiver 114. The satellite 110 is arranged to be able to communicate wirelessly with the transceiver 106 of the satellite gateway 104 and with the transceiver(s) 114 of the client system(s) 112, and thereby provide a link 107 for routing internet traffic between the source or destination on the internet 102 and the client system(s) 112. For example the satellite link 107 and transceivers 106, 114 may operate on the Ka microwave band (26.5 to 40 GHz).
In one model the operator of the satellite 110 and/or gateway 104 sells bandwidth to a downstream internet service provider (ISP), who in turn sells an internet access service based on that bandwidth to a plurality of end users 116. The end users 116 may be individual people (consumers) or businesses. Depending on implementation, the one or more client systems 112 may comprise a central satellite base station run by the ISP (the base station comprising the transceiver 114), and a local communication infrastructure providing access onwards to the equipment of a plurality of users within the region in question. E.g. the local communication infrastructure may comprise a relatively short range wireless technology or a local wired infrastructure, connecting onwards to home or business routers or individual user terminals. Alternatively or additionally, the client systems 112 may comprise individual, private base stations each with its own satellite transceiver 114 for connecting to the satellite 110 and local access point for connecting to one or more respective user terminals. In this case the ISP does not necessarily provide any extra infrastructure, but acts as a broker for the bandwidth provided by the satellite 110. For example an individual femtocell or picocell could be located in each home or business, each connecting to a respective one or more user terminals using a short range wireless technology, e.g. a local RF technology such as Wi-Fi.
Referring to FIG. 2 by way of example, the satellite 110 is deployed in a geostationary orbit and arranged so that its field of view or signal covers roughly a certain geographic region 200 on the Earth's surface. FIG. 2 shows South Africa as an example, but this could equally be any other country or region within any one or more countries (e.g. a state, county or province, or some other non-politically defined region).
Furthermore, referring to FIGS. 2 and 3, using modern techniques the satellite 110 may be configured as a spot-beam satellite based on a beam-forming technology, so that the communications between the satellite 110 and the client equipment 112 in the covered region 200 are divided amongst a plurality of spatially distinct beams 202. A beam refers to a volume of space or “lobe” in which transmission and/or reception of one or more given signals are approximately confined, typically a signal cone. Each beam 202 is directed in a different respective direction such that beams are arranged into a cluster, each beam covering a different respective (sub) area on the Earth's surface within the region 200 in question (though the areas covered by the beams 202 may be arranged to overlap somewhat to avoid gaps in coverage). This is a way of increasing capacity, as the limited frequency band of the satellite 110 (e.g. Ka band) can be re-used separately in different beams 202—i.e. it provides a form of directional spatial division multiplexing (though adjacent beams may still use different bands or sub-bands, especially if they overlap in space). By way of example FIG. 2 shows five beams 202a-202e which between them approximately cover the area of South Africa, but it will be appreciated that other numbers and/or sizes of beam are also possible.